JP2023545445A - Push-pull power supply for multi-mesh processing chambers - Google Patents

Abstract

A radio frequency (RF) power circuit for a multi-electrode cathode of a processing chamber may include an RF source and one or more inductive elements conductively coupled to the RF source. The first inductive element may be inductively coupled to the one or more inductive elements, the first inductive element receiving a first portion of RF power emitted from the RF source, and the first inductive element receiving a first portion of RF power emitted from the RF source. may be configured to supply a portion of the processing chamber to a first pedestal electrode of the processing chamber. A second inductive element may also be inductively coupled to the one or more inductive elements, the second inductive element receiving a second portion of RF power transmitted from the RF source through the one or more inductive elements. and may be configured to provide a second portion of RF power to the second pedestal electrode. [Selection diagram] Figure 5

Description

CROSS-REFERENCES TO RELATED APPLICATIONS This application has the benefit and priority of U.S. Nonprovisional Application No. 17/068,994, entitled "PUSH-PULL POWER SUPPLY FOR MULTI-MESH PROCESSING CHAMBERS," filed October 13, 2020. , the entire contents of which are incorporated herein by reference.

The present disclosure generally relates to systems and methods for regulating plasma in semiconductor substrate manufacturing processes. More specifically, this disclosure describes systems and methods for controlling individual radio frequency (RF) voltages applied to different conductive meshes of a pedestal to uniformly control a plasma.

In the manufacture of integrated circuits and other electronic devices, plasma processes are often used to deposit or etch various layers of materials. A plasma enhanced chemical vapor deposition (PECVD) process is a chemical process in which electromagnetic energy is applied to at least one precursor gas or vapor to convert the precursor into a reactive plasma. The plasma can be generated inside the processing chamber, ie, in situ, or it can be generated with a remote plasma generator positioned remotely from the processing chamber. This process is widely used to deposit materials onto substrates to produce high quality, high performance semiconductor devices.

Transistor structures are becoming increasingly complex and difficult as feature sizes shrink. To meet processing demands, advanced process control techniques are useful to contain costs and maximize substrate and die yields. Typically, if the plasma is not uniformly controlled across the surface area of the substrate, die at specific locations on the substrate are subject to yield problems. At the substrate processing level, advances in process uniformity control are required when controlling the plasma, allowing not only global process adjustments across the substrate, but also fine localized process adjustments. Therefore, there is a need for a method and apparatus that allows fine, localized process adjustments across a substrate.

[0005] In some embodiments, a radio frequency (RF) power circuit for a multi-electrode cathode of a processing chamber includes an RF source, one or more inductive elements conductively coupled to the RF source, and one or more inductive elements. a first inductive element inductively coupled to the element. A first inductive element receives a first portion of RF power emitted from the RF source through the one or more inductive elements, and transmits a first portion of RF power emitted from the RF source to a first portion of the processing chamber. may be configured to supply a pedestal electrode. The power supply circuit may also include a second inductive element inductively coupled to the one or more inductive elements. A second inductive element receives a second portion of RF power emitted from the RF source through the one or more inductive elements, and receives a second portion of RF power emitted from the RF source into a second portion of the processing chamber. may be configured to supply a pedestal electrode.

[0006] In some embodiments, an RF power circuit for a multi-electrode cathode of a processing chamber receives an RF source and a first portion of RF power transmitted from the RF source; and a first inductive element that may be configured to provide a first portion of RF power to a first pedestal electrode of the processing chamber. The power supply circuit is configured to receive a second portion of RF power transmitted from the RF source and to supply the second portion of RF power transmitted from the RF source to a second pedestal electrode of the processing chamber. A second inductive element may also be included. The power supply circuit may also include a capacitive element that may separate the first inductive element from the second inductive element.

[0007] In some embodiments, a method of powering a multi-electrode cathode of a processing chamber includes generating RF power using an RF source and through one or more inductive elements conductively coupled to the RF source. transmitting RF power; inductively coupling a first portion of the RF power from the one or more inductive elements to the first inductive element; and processing the first portion of the RF power from the first inductive element. providing a first pedestal electrode of the chamber; inductively coupling a second portion of the RF power from the one or more inductive elements to the second inductive element; and inductively coupling the second portion of the RF power to the second inductive element. from the inductive element to a second pedestal electrode of the processing chamber.

[0008] In any embodiment, any and/or all of the following features may be included in any combination, without limitation. The one or more inductive elements may include a third inductive element and a fourth inductive element, the third inductive element may be inductively coupled to the first inductive element, and the fourth inductive element may be inductively coupled to the first inductive element. may be inductively coupled to the second inductive element. The power supply circuit may also include a first DC source conductively coupled to the first inductive element and a second DC source conductively coupled to the second inductive element, and the capacitive element is coupled to the first DC source. The DC source may be isolated from the second DC source. The voltage difference between the first DC source and the second DC source may represent a bipolar chuck voltage that holds the substrate on the pedestal in the processing chamber. The power supply circuit also includes a tuned circuit configured to siphon off a portion of the RF power such that the power supplied to the first pedestal electrode is different from the power supplied to the second pedestal electrode. may be included. The tuned circuit may include a parasitic inductor. The tuned circuit may include parasitic capacitors. The first pedestal electrode may include a wire mesh. The phase difference between the RF source and the second RF source can rotate the energy transferred to the plasma in the processing chamber. The first pedestal electrode, the second pedestal electrode, the third pedestal electrode, and the fourth pedestal electrode may be located in separate quadrants of the pedestal of the processing chamber. The first pedestal electrode may include a circular mesh at the center of the pedestal, and the second pedestal electrode may include a ring mesh at the outer periphery of the pedestal. The first inductive element may include an inductive value of approximately 1 μH.

[0009]
In any embodiment, the power circuit may also be inductively coupled to a second RF source, a second one or more inductive elements conductively coupled to the RF source, and a second inductive element or elements conductively coupled to the second RF source. a third inductive element, the third inductive element receiving the first portion of RF power transmitted from the second RF source through the second inductive element or elements; The processing chamber may be configured to provide a first portion of RF power emitted from two RF sources to a first pedestal electrode of the processing chamber. The power supply circuit may further include a fourth inductive element that can be inductively coupled to the second inductive element or elements, the fourth inductive element being a first inductive element of the RF power emitted from the second RF source. the second portion of the RF power transmitted from the second RF source to a second pedestal electrode of the processing chamber; . The third inductive element and the fourth inductive element may have the same inductance. The third inductive element and the fourth inductive element may be configured to block RF power transmitted from the RF source. The first inductive element and the second inductive element may be configured to block RF power emitted from the second RF source. The RF source may have a frequency of approximately 13 MHz and the second RF source may have a frequency of approximately 40 MHz.

[0010]
A further understanding of the nature and advantages of the disclosed technology can be gained by reference to the remaining portions of the specification and the drawings, in which like reference numerals refer to similar elements. used over the years. In some examples, sublabels are associated with reference numbers to indicate one of a plurality of similar components. References to reference numbers without specifying existing sublabels are intended to refer to all such multiple similar components.

1 is a cross-sectional view of a processing chamber according to some embodiments. FIG. FIG. 3 illustrates a configuration for two pedestal electrodes according to some embodiments. FIG. 7 illustrates an alternative configuration for multiple pedestal electrodes according to some embodiments. FIG. 3 illustrates a pedestal electrode configuration used to balance RF energy between a central portion of a support assembly and an outer portion of the support assembly according to some embodiments. FIG. 3 illustrates a power supply circuit configuration that uses inductive coupling to isolate electrical paths between different pedestal electrodes while maintaining an equalized push-pull signal between two pedestal electrodes according to some embodiments. FIG. 3 illustrates a power circuit that can inject two different RF signals into a pedestal electrode according to some embodiments. FIG. 3 illustrates a power supply circuit including a tuning circuit for skewing the uniformity of the RF signal sent to each pedestal electrode according to some embodiments. FIG. 3 illustrates a concentric arrangement of pedestal electrodes of a support assembly with a tuned circuit according to some embodiments. FIG. 3 is a diagram illustrating a power supply circuit in a four-quadrant implementation according to some embodiments. 10 is a series of diagrams illustrating the effect of a rotating RF field in the four-electrode configuration shown in FIG. 9 in accordance with some embodiments; FIG. FIG. 2 is a flow diagram illustrating a method for powering a multi-electrode cathode of a processing chamber according to some embodiments.

[0022] Embodiments for controlling a plasma across the surface area of a substrate are described herein. The present disclosure provides radio frequency (RF) circuits and methods for adjusting the distribution of RF power to a plurality of meshes embedded in a substrate support or pedestal that also functions as an electrostatic chuck. The methods and systems described herein may be characterized in that the implanted mesh is a source of RF power (e.g., one electrode or multiple electrodes) or that the mesh is a destination for RF power (e.g., ground). It can be applied regardless of whether Embodiments disclosed herein allow modulating the uniformity of the plasma profile above the substrate. Varying the plasma distribution provides improved uniformity of film parameters on the substrate, including, for example, deposition rate, film stress, refractive index, and other parameters.

[0023] FIG. 1 is a cross-sectional view of a processing chamber 100 according to some embodiments. As illustrated, processing chamber 100 may be an etch chamber suitable for etching a substrate 154. Examples of processing chambers that may be adapted to benefit from the embodiments described herein include the Producer® Etch Processing Chamber, commercially available from Applied Materials, Inc., located in Santa Clara, California; Precision™ Processing Chamber may be mentioned. It is contemplated that other processing chambers, including those from other manufacturers, may be adapted to benefit from these embodiments.

[0024] Processing chamber 100 may be used for a variety of plasma processes. For example, processing chamber 100 may be used to perform dry etching using one or more etchants. The processing chamber can be used for plasma ignition from precursors C _x F _y (where x and y represent known compound values), O ₂ , NF ₃ , or combinations thereof. In another example, processing chamber 100 may be used for a plasma enhanced chemical vapor deposition (PECVD) process using one or more precursors.

[0025] Processing chamber 100 may include a chamber body 102, a lid assembly 106, and a support assembly 104. Lid assembly 106 is positioned at the upper end of chamber body 102 . Support assembly 104 may be disposed within chamber body 102 and lid assembly 106 may be coupled to chamber body 102 to enclose support assembly 104 within processing region 120. Chamber body 102 may include a transfer port 126 that may include a slit valve formed in a sidewall of chamber body 102 . Transfer port 126 may be selectively opened and closed to allow access to the interior of processing area 120 by a substrate handling robot (not shown) for substrate transfer.

[0026] Electrode 108 may be provided as part of lid assembly 106. Electrode 108 may also function as a gas distribution plate 112 having a plurality of openings 118 for receiving process gas into processing region 120. Process gases may be supplied to processing chamber 100 via conduit 114 and may enter gas mixing region 116 before flowing through opening 118. Electrode 108 may be coupled to a power source such as an RF generator, DC power, pulsed DC power, pulsed RF, or the like. Isolator 110 can contact electrode 108 and electrically and thermally isolate electrode 108 from chamber body 102 . Isolator 110 may be constructed using dielectric materials such as aluminum oxide, aluminum nitride, and/or other ceramic or metal oxides. Heater 119 may be coupled to gas distribution plate 112. Heater 119 may also be coupled to an AC power source.

[0027] The support assembly 104 may be coupled to the lift mechanism via a shaft 144 that extends through the bottom of the chamber body 102. The lift mechanism may be flexibly sealed to the chamber body 102 by a bellows that prevents vacuum leakage around the shaft 144. The lift mechanism may enable vertical movement of the support assembly 104 between a transfer position and multiple process positions within the chamber body 102 to place the substrate 154 in close proximity to the electrode 108.

[0028] Support assembly 104 may be formed from a metallic or ceramic material. For example, metal oxides, nitrides, or oxide/nitride mixtures, such as aluminum, aluminum oxide, aluminum nitride, aluminum oxide/nitride mixtures, and/or other similar materials can be used. In typical implementations, support assembly 104 may include one or more pedestal electrodes. One or more pedestal electrodes may be configured to provide RF energy to the plasma in processing region 120. For example, an RF source 160 may be provided outside the chamber body 102 to provide RF energy to one or more pedestal electrodes of the support assembly 104. RF energy may be transmitted through one or more pedestal electrodes to the gas in the processing region 120 that is deposited through the gas distribution plate 112 (also referred to as a "showerhead") to generate a plasma. A plasma may be maintained above the substrate 154 to deposit a layer of material onto the substrate 154. In order to uniformly deposit material onto the substrate 154, the energy transferred to the plasma should be maintained uniformly across the surface area of the substrate 154.

[0029] A number of technical challenges can create difficulties in maintaining this uniform plasma. The first technical issue involves the size of the substrate 154 in relation to the wavelength size of the RF energy applied to the plasma. RF source 160 may operate at a typical voltage, such as about 13 MHz. If the substrate 154 is approximately 2.0 m to 2.5 m, the wavelength magnitude at 13 MHz may be a significant fraction of the diameter of the substrate 154. Inside a plasma environment, the wavelength can effectively be reduced by a factor of two or three. For example, as the quarter wavelength oscillates between minimum and maximum voltages, a standing wave may be formed across the surface of the substrate 154 as energy is transferred to the plasma in the chamber body 102. This may result in significant non-uniformity in the plasma and non-uniform deposition of material onto the substrate 154. This effect becomes even more pronounced at high voltages such as 40 MHz, where the total wavelength may be comparable to the size of substrate 154. When the waves oscillate, there are regions of maximum plasma voltage and regions of zero voltage, which can result in a highly non-uniform process. Therefore, when the standing wave generated by the pedestal electrodes rotates or otherwise moves over time, the RF voltage across multiple pedestal electrodes is such that non-uniformities can be averaged out over time. A solution is needed to modulate the As discussed below, RF signals may be applied to multiple electrodes at multiple points on support assembly 104, and/or the shape of the standing wave may change the phase of different RF signals applied to different electrodes. It can be modulated by adjusting. As the standing wave pattern moves quickly across the plasma, the inhomogeneities average out over time and the plasma can maintain a certain crystalline refraction and remain amorphous.

[0030] A second technical problem includes ensuring that the RF signals provided to each of the plurality of pedestal electrodes are equal. For example, in FIG. 1, a method known as bipolar chucking using a first pedestal electrode 172 and a second pedestal electrode 174 is used. Bipolar chucking is a method of applying a DC voltage difference between the first pedestal electrode 172 and the second pedestal electrode 174. This electrostatic difference serves to hold the substrate 154 to the support assembly 104. This may be contrasted with monopolar chucking, where only a single pedestal electrode is used or a DC voltage is applied to only a single pedestal electrode. Monopolar chucking becomes effective only when energy is applied to the plasma to complete the circuit. Bipolar chucking uses two separate electrical paths from RF source 160 to each of first pedestal electrode 172 and second pedestal electrode 174. In the example of FIG. 1, a first DC voltage source 162 is applied to the first electrical path of the first pedestal electrode 172. A second DC voltage source 164 is applied to a second electrical path of a second pedestal electrode 174 . The first electrical path may include a first capacitor 166 and the second electrical path may include a second capacitor 168 to isolate the DC voltage sources 162, 164 from each other. In some embodiments, each capacitor 166, 168 may be relatively large, such as 50 nF, to block DC voltage. However, splitting the output of the RF source 160 into two electrical paths may result in a different amount of RF energy being transmitted to each pedestal electrode 172, 174. Therefore, a solution is needed to maintain insulation while ensuring push-pull equalization between the two pedestal electrodes 172, 174.

[0031] A first pedestal electrode 172 and a second pedestal electrode 174 may be provided on the support assembly 104. First pedestal electrode 172 and second pedestal electrode 174 may be embedded within support assembly 104 and/or coupled to a surface of support assembly 104. The first pedestal electrode 172 and the second pedestal electrode 174 may be a plate, perforated plate, mesh, wire screen, or any other distributed conductive arrangement. Although only two pedestal electrodes are illustrated in FIG. 1, other embodiments use more than two pedestal electrodes with different geometries and/or placements in support assembly 104, as described in detail below. be able to.

[0032] FIG. 2 is a diagram illustrating a two pedestal electrode configuration according to some embodiments. In this example, first pedestal electrode 172 and second pedestal electrode 174 may divide support assembly 104 in half, with pedestal electrodes 172, 174 each occupying substantially about half of support assembly 104. It is arranged like this. For example, each pedestal electrode 172, 174 may have a "D" or semicircular shape that occupies approximately half the area of the support assembly 104. A gap may be maintained between the two pedestal electrodes 172 , 174 at the center of the support assembly 104 so that the pedestal electrodes 172 , 174 may remain electrically isolated from each other within the support assembly 104 .

[0033] FIG. 2 illustrates each pedestal electrode 172, 174 as a wire mesh formed in a rectangular pattern. For example, the wire mesh may be formed from a material such as molybdenum that has a similar coefficient of thermal expansion to the material used for support assembly 104. This causes support assembly 104 and pedestal electrodes 172, 174 to uniformly expand and contract as heat is applied to support assembly 104 and substrate 154 during operation of the processing chamber. In some embodiments, the mesh rectangular pattern formed by the pedestal electrodes 172, 174 may include a regular rectangular pattern with a pitch of about 1.0 mm with wires about 0.05 mm thick.

[0034] FIG. 3 is a diagram illustrating an alternative configuration of multiple pedestal electrodes according to some embodiments. In this example, support assembly 104 may include four pedestal electrodes 302 , 304 , 306 , 308 positioned in quadrants of support assembly 104 . Each electrode 302, 304, 306, 308 may be formed using wire mesh, as described above. The wire mesh may be arranged to form a pie-shaped geometry that substantially fills a quadrant of the support assembly 104. Note that the four pedestal electrodes 302, 304, 306, 308 illustrated in FIG. 3 are provided by way of example only and not limitation. In other embodiments, more or fewer pedestal electrodes may be used by dividing the geometry of support assembly 104 into any number of subsections. For example, eight pedestal electrodes may be used by dividing the support assembly 104 into eight octants, and the pedestal electrodes may be formed to substantially fill each of the resulting eight octants. .

[0035] FIG. 4 is a diagram illustrating a pedestal electrode configuration used to balance RF energy between a central portion of support assembly 104 and an outer portion of support assembly 104, according to some embodiments. . In this example, first pedestal electrode 404 may form a first circular shape as a circular mesh that generally occupies a central portion of support assembly 104 . The second pedestal electrode 402 forms a ring around the first pedestal electrode 404 to substantially occupy the remaining space between the outer edge of the support assembly 104 and the outer boundary of the first pedestal electrode 404. A ring mesh may be formed. The second pedestal electrode 402 may form a concentric ring around the first pedestal electrode 404. This geometry allows a first RF signal to be applied to the central first pedestal electrode 404 and a second RF signal to be applied to the second pedestal electrode 402. Adjusting the relative phase between these two RF signals can be used to oscillate the shape of the energy generated in the plasma between the central portion of support assembly 104 and the outer portion of support assembly 104.

[0036] FIG. 5 illustrates an RF power circuit 570 that uses inductive coupling to isolate electrical paths between different pedestal electrodes while maintaining an equalized push-pull signal between two pedestal electrodes, according to some embodiments. FIG. RF power circuit 570 may include RF source 502. A variety of frequencies may be used for the RF source, from the low end of 350 kHz to frequencies in the very high frequency (VHF) range. For example, in some embodiments, frequencies such as 13.56 MHz, 27.12 MHz, or 40.68 MHz may be used. RF source 502 may propagate RF power and generate RF signals described as originating from RF source 502. RF source 502 may be coupled in series with one or more inductive elements. For example, FIG. 5 illustrates an inductive element 504 and another inductive element 506. In some embodiments, the value of the inductive elements 504, 506 is approximately equal to a value, such as about 1 μH, and may range from about 0.1 μH to about 10 μH. RF source 502, inductive element 504, and inductive element 506 may form a continuous circuit path in power circuit 570 that may be referred to as a “first” circuit path. The one or more inductive elements may include two discrete inductive elements, such as inductive element 504 and inductive element 506. Also, the one or more inductive elements may include more or less than two inductive elements. The one or more inductive elements may also be conductively coupled to the RF source 502 through a conductive or wired path, as shown in FIG. 5, which may be contrasted with conventional inductive coupling.

[0037] Power circuit 570 may also include a second circuit path that may be conductively isolated from the first circuit path. Instead of having a direct conductive path, the second circuit path may be inductively coupled to the first circuit path. For example, the second circuit path may include inductive element 508 and another inductive element 510. These inductive elements 508, 510 may be inductively coupled to the inductive elements 504, 506 such that an RF signal provided from the RF source 502 is communicated from the inductive elements 504, 506 to the inductive elements 508, 510. In some embodiments, inductive element 504 and inductive element 508 may be interleaved in a toroidal configuration to maximize inductive coupling between inductive elements 504, 508. Inductive element 506 and inductive element 510 may be arranged in a similar manner.

[0038] Inductive element 508 and inductive element 510 may be separated by capacitive element 512. Capacitive element 512 may be implemented using a capacitor having a relatively large capacitance value, such as about 50 nF or more. The capacitance value of capacitive element 512 provides a low impedance to RF signals from RF source 502 and blocks any DC signals that would otherwise pass between inductive element 508 and inductive element 510. It can be relatively large so that it is large enough to Note that when inductive element 504 and inductive element 506 are referred to as "inductive element(s)," inductive element 508 and inductive element 510 may be referred to as first/second inductive elements, respectively.

[0039] Power supply circuit 570 may also include a first DC voltage source 162 and a second DC voltage source 164. A first DC voltage source 162 may be conductively coupled to inductive element 508 and a second DC voltage source 164 may be conductively coupled to element 510. The first DC voltage source 162 and the second DC voltage source 164 may be configured such that a voltage difference may be established between the first DC voltage source 162 and the second DC voltage source 164. Capacitive element 512 may isolate the DC signal from first DC voltage source 162 from the second DC voltage source 164 in RF power circuit 570 . A voltage difference between these DC voltage sources 162, 164 may be established across capacitive element 512.

[0040] The output of the inductive element 508 conductively coupled to the first DC voltage source 162 may be coupled to the first pedestal electrode 172. Similarly, the output of inductive element 510 that is conductively coupled to second DC voltage source 164 may also be conductively coupled to second pedestal electrode 174 . These RF signals may pass through two rods that provide an electrical path to the pedestal electrodes 172, 174. This arrangement allows the voltage difference between the first DC voltage source 162 and the second DC voltage source 164 to use bipolar chucking to hold the substrate 154 on the support assembly 104. . Accordingly, inductive element 508 is inductively coupled to one or more inductive elements (e.g., inductive elements 508, 510) and receives a first portion of RF power transmitted from an RF source through the one or more inductive elements. , may be considered a “first” inductive element configured to provide a first portion of RF power emitted from the RF source to the first pedestal electrode 172 of the processing chamber 120. Similarly, inductive element 510 is inductively coupled to one or more inductive elements (e.g., inductive elements 508, 510) and receives a second portion of RF power transmitted from the RF source through the one or more inductive elements. However, it can be considered a "second" inductive element configured to provide a second portion of RF power emitted from the RF source to the second pedestal electrode 174 of the processing chamber 120.

[0041] Capacitive element 512 may function as a blocking capacitor to provide DC isolation between the two pedestal electrodes 172, 174. This enables bipolar chucking and allows RF to pass through the capacitive element 512. This arrangement also establishes a push-pull relationship between the RF signals coupled to the first pedestal electrode 172 and the second pedestal electrode 174. This makes the signals the same at each pedestal electrode 172, 174. When RF signals are provided to support assembly 104 by pedestal electrodes 172, 174 having a push-pull relationship, the two electrode positions may each be approximately 180 degrees out of phase.

[0042] In one implementation, second pedestal electrode 174 may have a larger surface area than first pedestal electrode 172. In one implementation, second pedestal electrode 174 may have a larger diameter than first pedestal electrode 172. A second pedestal electrode 174 may surround the first pedestal electrode 172. In one implementation, first pedestal electrode 172 can function as a chuck electrode while functioning as a first RF electrode. The second pedestal electrode 174 may be a second RF electrode that conditions the plasma along with the first pedestal electrode 172. First pedestal electrode 172 and second pedestal electrode 174 may apply power at the same frequency or may apply power at different frequencies. The RF power to one or both of the first pedestal electrode 172 and the second pedestal electrode 174 can be varied to tune the plasma. For example, sensors (not shown) may be used to monitor RF energy from one or both of first pedestal electrode 172 and second pedestal electrode 174. Data from the sensor device may be communicated and utilized to vary the power applied to the RF source of the first pedestal electrode 172 and/or the RF source 502 of the second pedestal electrode 174.

[0043] As used herein, the terms first, second, third, fourth, fifth, etc. are used merely to distinguish between different instances of similar circuit elements. For example, "first" inductive element 508 may be distinguished from "second" inductive element 510. This term does not imply any order, priority, importance, or any other substantive characteristic of the elements, and is only used to distinguish one element from another. Note also that this allows the first/second label to be used to distinguish between any two elements. Therefore, these labels are relative rather than absolute.

[0044] FIG. 6 is a diagram illustrating a power supply circuit 670 that may inject two different RF signals into a pedestal electrode according to some embodiments. In this example, a second RF source 602 may be added to power supply circuit 670. In some embodiments, RF source 502 may use a frequency of 13.56 MHz and second RF source 602 may use a 40.68 MHz signal. The frequency of second RF source 602 may be different than the frequency of RF source 502. The second RF source 602 may form a third circuit path that includes inductive elements 604, 606 arranged as described above for the first circuit path of the RF source 502. The third circuit path may be inductively coupled to the second circuit path using inductive elements 608, 610 separated by a capacitive element 612. Capacitive element 612 may be similar to capacitive element 512 and has a relatively large capacitance value, such as about 50 nF or more, thereby isolating first DC voltage source 162 from second DC voltage source 164. The condition is maintained. In some cases, the values of the inductive elements 604, 606, 608, 610 between the first and third circuit paths are the values used for the inductive elements 504, 506, 508, 510 between the first and second circuit paths. It may be different from For example, inductive elements 604, 606, 608, 610 may be configured with an inductance value that passes RF signals from second RF source 602 while blocking RF signals from RF source 502. Similarly, inductive elements 504, 506, 508, 510 may be configured to have an inductance value that passes RF signals from RF source 502 while blocking RF signals from second RF source 602.

[0045] This arrangement allows two different frequencies to be injected into the pedestal electrodes 172, 174 simultaneously. Note that the use of two pedestal electrodes 172, 174 is provided by way of example only and is not limiting. In other embodiments, any number of pedestal electrodes can be used by replicating the circuit elements shown in FIG. Similarly, the use of two different frequencies is provided by way of example only and is not meant to be limiting. In other embodiments, any number of different frequencies can be injected into the pedestal electrode by replicating the circuit path shown in FIG. 6 using RF sources with different frequencies and corresponding inductance values.

[0046] FIG. 7 is a diagram illustrating a power supply circuit 770 that includes a tuning circuit for skewing the uniformity of the RF signal sent to each pedestal electrode 172, 174, according to some embodiments. Power supply circuit 770 of FIG. 7 is similar to RF power supply circuit 570 of FIG. 5 except that a tuning circuit is added to the input of first pedestal electrode 172. Power supply circuit 770 of FIG. The tuning circuit may include a parasitic inductor 702 and/or a parasitic capacitor 704 to sink current from the RF signal before being applied to the first pedestal electrode 172. As a result, this causes the RF signals sent by the first pedestal electrode 172 and the second pedestal electrode 174 to be asymmetric. This can be used to compensate for irregularities in the processing chamber. Although an ideal processing chamber could benefit from purely symmetrical RF power, many processing chambers (especially small chambers) rely on the electrical and/or physical properties of the processing chamber to Specific abnormalities may occur. A tuned circuit can be used to adjust the output of one side of the power supply circuit 772 to compensate for processing chamber abnormalities. For example, adjusting the RF output of the first pedestal electrode 172 using a parasitic capacitor 704 and/or a parasitic inductor 702 can be used to skew the RF waveform generated in the plasma from one side to the other.

[0047] FIG. 8 is a diagram illustrating a concentric arrangement of pedestal electrodes 802, 804 in a support assembly 104 with tuned circuitry, according to some embodiments. Power supply circuit 770 in FIG. 8 may be the same as power supply circuit 770 in FIG. 7. However, the first pedestal electrode 802 may form a circular wire mesh at the center of the support assembly 104 and the second pedestal electrode 804 may form a concentric ring at the outer periphery of the support assembly 104. For example, first pedestal electrode 802 and second pedestal electrode 804 may be arranged as shown in FIG. 4. A tuned circuit can be used as described above to compensate for processing chamber anomalies by skewing the RF waveform generated in the plasma with respect to center-to-edge non-uniformities caused by the processing chamber. .

[0048] FIG. 9 is a diagram illustrating a power supply circuit 970 for a four-quadrant implementation, according to some embodiments. First pedestal electrode 910 and second pedestal electrode 916 may occupy opposite quadrants of support assembly 104, as shown in FIG. Similarly, third pedestal electrode 912 and fourth pedestal electrode 914 may also occupy opposing quadrants. The circuits of the power supply circuit 970 that drive the first/second pedestal electrodes 910, 916 (e.g., RF source 502, inductive elements 504, 506, 508, 510, capacitive element 512, etc.) are connected to the third/fourth pedestal electrodes 910, 916. Electrodes 912, 914 (eg, RF source 902, inductive elements 904, 906, 908, 910, capacitive element 913, tuned circuit capacitor 915, and tuned inductor 999) can be replicated to individually power them.

[0049] This configuration creates a rotating push-pull circuit that rotates the oscillating field circularly around the plasma. In some embodiments, the frequency difference between RF source 502 and RF source 902 can control the speed at which the field rotates in the plasma. For example, the frequency difference may be about 1 kHz to about 100 kHz. For a 1 kHz difference, rotation around the plasma may take approximately 1 millisecond, and for a 100 kHz difference, rotation around the plasma may take approximately 10 microseconds. Generally, rotational speeds within this range are desirable so that the movement of the field in the plasma is sufficient to average out any instantaneous inhomogeneities over time. In some embodiments, the frequency difference may be kept at 5 kHz or higher to avoid problems with reflected power fluctuations that can make it difficult for the RF source 502 to generate stable power.

[0050] FIG. 10 is a series of diagrams illustrating the effect of a rotating RF field in the four-electrode configuration shown in FIG. 9, according to some embodiments. In this example, the mesh may be subdivided into four paired quadrants on support assembly 104. When operating in a push-pull drive configuration, the standing wave is capable of both oscillating and rotating around the plasma. When the push-pull pairs operate at slightly different frequencies, the overall push-pull across the diameter of the plasma rotates smoothly with a speed equal to the frequency difference and can move back and forth between different mesh combinations. A tuning element can be added as shown in FIG. 9, or a push-pull phase difference offset from 180 degrees can be introduced to add a center-to-edge component that also rotates.

[0051] FIG. 11 is a flow diagram 1100 illustrating a method for powering a multi-electrode cathode of a processing chamber, according to some embodiments. The method may include generating 1102 RF power using an RF source. The RF source can use any of the frequencies mentioned above and can be integrated into the power circuit, as illustrated by RF source 502 in FIGS. 5-9 above.

[0052] The method may also include transmitting RF power through one or more inductive elements conductively coupled to the RF source (1104). The one or more inductive elements may include one or more inductors, such as inductive elements 504, 506 shown in FIGS. 5-9 above. Note that a single inductive element may be used, or in different embodiments more than one inductive element.

[0053] The method may additionally include inductively coupling (1106) a first portion of RF power from the one or more inductive elements to the first inductive element. For example, the first portion of RF power may be the portion of RF power from RF source 502 that is inductively coupled from inductive element 504 to inductive element 508 in FIGS. 5-9 above.

[0054] The method may further include providing (1108) a first portion of RF power from the first inductive element to a first pedestal electrode of the processing chamber. For example, this first portion of RF power may be provided from the inductive element 508 to the first pedestal electrode 172 as shown in FIGS. 5-9 above.

[0055] The method may also include inductively coupling (1110) a second portion of RF power from the one or more inductive elements to the second inductive element. For example, the second portion of RF power may be the portion of the RF power from RF source 502 that is inductively coupled from inductive element 506 to inductive element 510 in FIGS. 5-9 above.

[0056] The method may additionally include providing (1112) a second portion of RF power from the second inductive element to a second pedestal electrode of the processing chamber. For example, this second portion of RF power may be provided from the inductive element 510 to the second pedestal electrode 174 as shown in FIGS. 5-9 above.

[0057] It should be appreciated that the specific steps illustrated in FIG. 11 provide a particular method of powering a multi-electrode cathode of a processing chamber according to various embodiments. Other orders of steps may also be performed according to alternative embodiments. For example, alternative embodiments may perform the steps outlined above in a different order. Furthermore, the individual steps shown in FIG. 11 may include multiple substeps that may be performed in various orders appropriate to the individual steps. Furthermore, further steps may be added or removed depending on the particular application. Many variations, modifications, and alternatives also fall within the scope of this disclosure.

[0058] The term "about" throughout this disclosure may be used to describe a value that occurs within a range of -15% to +15% of the stated value. For example, a capacitance of approximately 100 nF may fall within the range of 85 nF to 115 nF.

[0059] In the above description, for purposes of explanation, numerous specific details are set forth to provide a thorough understanding of the various embodiments. However, it will be apparent to those skilled in the art that some embodiments may be practiced without some of these specific details. In other instances, well-known structures and devices are shown in block diagram form.

[0060] The foregoing description provides example embodiments only and is not intended to limit the scope, applicability, or configuration of the present disclosure. Rather, the foregoing description of various embodiments will provide those skilled in the art with an enabling disclosure for implementing at least one embodiment. It should be understood that various changes may be made in the function and arrangement of elements without departing from the spirit and scope of the several embodiments as defined in the following claims.

[0061] The foregoing description sets forth specific details to provide a thorough understanding of the embodiments. However, one of ordinary skill in the art will understand that the embodiments may be practiced without these specific details. For example, circuits, systems, networks, processes, and other components may be shown as components in block diagram form in order not to obscure the embodiments in unnecessary detail. In other instances, well-known circuits, processes, algorithms, structures, and techniques may be shown without unnecessary detail in order not to obscure the embodiments.

[0062] Note also that the particular embodiments may be described as processes illustrated as flowcharts, flow diagrams, data flow diagrams, structural diagrams, or block diagrams. Although a flowchart may depict the steps as a continuous process, many of the steps can be performed in parallel or simultaneously. Furthermore, it is also possible to change the order of the steps. A process ends when its steps are completed, but may have additional steps not included in the diagram. A process may correspond to a method, function, procedure, subroutine, subprogram, etc. If the process corresponds to a function, its termination may correspond to the function returning to the calling function or main function.

[0063] Although features have been described in the foregoing specification with reference to specific embodiments thereof, it should be appreciated that not all embodiments are limited thereto. Various features and aspects of several embodiments may be used individually or jointly. Furthermore, embodiments may be utilized in any number of environments and applications beyond those described herein without departing from the broader spirit and scope of this specification. Accordingly, the specification and drawings are to be regarded in an illustrative rather than a restrictive sense.

Claims (20)

A radio frequency (RF) power circuit for a multi-electrode cathode of a processing chamber, the circuit comprising:
an RF source;
one or more inductive elements conductively coupled to the RF source;
a first inductive element inductively coupled to the one or more inductive elements, the first inductive element receiving through the one or more inductive elements a first portion of RF power emitted from the RF source; a first inductive element configured to supply a first portion of RF power emitted from the processing chamber to a first pedestal electrode of the processing chamber;
a second inductive element inductively coupled to the one or more inductive elements, the second inductive element receiving through the one or more inductive elements a second portion of RF power emitted from the RF source; a second inductive element configured to supply a second portion of RF power emitted from the processing chamber to a second pedestal electrode of the processing chamber. The one or more inductive elements include a third inductive element and a fourth inductive element, the third inductive element being inductively coupled to the first inductive element, and the fourth inductive element being inductively coupled to the first inductive element. The RF power circuit of claim 1, wherein the RF power circuit is inductively coupled to the second inductive element. a second RF source;
a second inductive element or elements conductively coupled to the RF source;
a third inductive element inductively coupled to the second inductive element or elements, the third inductive element inductively coupling a first portion of the RF power emitted from the second RF source to the second inductive element or elements; a third inductive element configured to receive through the inductive element and provide a first portion of RF power emitted from the second RF source to a first pedestal electrode of the processing chamber;
a fourth inductive element inductively coupled to the second inductive element or elements, the fourth inductive element inductively coupled to the second inductive element or elements; a fourth inductive element configured to receive through the inductive element and provide a second portion of RF power emitted from the second RF source to a second pedestal electrode of the processing chamber. , RF power supply circuit according to claim 1. The RF power supply circuit according to claim 3, wherein the third inductive element and the fourth inductive element have the same inductance. 4. The RF power circuit of claim 3, wherein the third inductive element and the fourth inductive element are configured to block RF power emitted from the RF source. 6. The RF power circuit of claim 5, wherein the first inductive element and the second inductive element are configured to block RF power originating from the second RF source. 4. The RF power circuit of claim 3, wherein the RF source has a frequency of about 13 MHz and the second RF source has a frequency of about 40 MHz. An RF power circuit for a multi-electrode cathode of a processing chamber, the circuit comprising:
an RF source;
configured to receive a first portion of RF power transmitted from the RF source and provide a first portion of RF power transmitted from the RF source to a first pedestal electrode of the processing chamber. a first inductive element;
and configured to receive a second portion of RF power emitted from the RF source and to provide a second portion of RF power emitted from the RF source to a second pedestal electrode of the processing chamber. a second inductive element;
and a capacitive element separating the first inductive element from the second inductive element. a first DC source conductively coupled to the first inductive element;
9. The RF device of claim 8, further comprising a second DC source conductively coupled to the second inductive element, the capacitive element isolating the first DC source from the second DC source. power circuit. 10. The RF power circuit of claim 9, wherein the voltage difference between the first DC source and the second DC source represents a bipolar chuck voltage that holds a substrate on a pedestal in a processing chamber. further comprising a tuning circuit configured to sink a portion of the RF power such that the power supplied to the first pedestal electrode is different from the power supplied to the second pedestal electrode. 9. The RF power supply circuit according to claim 8, comprising: 12. The RF power circuit of claim 11, wherein the tuned circuit includes a parasitic inductor. 12. The RF power circuit of claim 11, wherein the tuning circuit includes a parasitic capacitor. 9. The RF power circuit of claim 8, wherein the first pedestal electrode includes a wire mesh. A method of powering a multi-electrode cathode of a processing chamber, the method comprising:
generating RF power using an RF source;
transmitting RF power through one or more inductive elements conductively coupled to the RF source;
inductively coupling a first portion of the RF power from the one or more inductive elements to a first inductive element;
providing a first portion of the RF power from the first inductive element to a first pedestal electrode of the processing chamber;
inductively coupling a second portion of the RF power from the one or more inductive elements to a second inductive element;
providing a second portion of the RF power from the second inductive element to a second pedestal electrode of the processing chamber. generating second RF power using a second RF source;
transmitting the second RF power through a second inductive element or elements conductively coupled to the second RF source;
inductively coupling a first portion of the second RF power from the second inductive element or elements to a third inductive element;
providing a first portion of the RF power from the third inductive element to a third pedestal electrode of the processing chamber;
inductively coupling a second portion of the second RF power from the second inductive element or elements to a fourth inductive element;
16. The method of claim 15, further comprising providing a second portion of the second RF power from the fourth inductive element to a fourth pedestal electrode of the processing chamber. 17. The method of claim 16, wherein a phase difference between an RF source and the second RF source rotates the energy transferred to the plasma of the processing chamber. 17. The method of claim 16, wherein the first pedestal electrode, the second pedestal electrode, the third pedestal electrode, and the fourth pedestal electrode are each located in separate quadrants of a pedestal of the processing chamber. 16. The method of claim 15, wherein the first pedestal electrode includes a circular mesh at the center of the pedestal and the second pedestal electrode includes a ring mesh at the outer periphery of the pedestal. 16. The method of claim 15, wherein the first inductive element includes an inductive value of about 1 [mu]H.

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